Purpose :
The Ahmed Glaucoma Valve (AGV) is a flow-restrictive glaucoma drainage device (GDD) that aims to reduce postoperative hypotony that may occur with other GDD and related complications. Xen-augmented Baerveldt (XAB) is a new technique developed to avoid hypotony after placement of the Baerveldt tube that can occur until encapsulation takes place around the plate. This study compared early safety and efficacy outcomes of AGV versus XAB implantation.

Methods :
Comparative case-series. Eleven consecutive eyes of glaucoma patients with indication for a GDD were scheduled to XAB implantation and compared with eleven age- and sex-matched individuals with previous AGV surgery. In all patients, number of ocular hypotensive drugs, intra-ocular pressure (IOP), best-corrected visual acuities (BCVA) and adverse events were gathered. The hypertensive phase was defined as an IOP > 21 mmHg during the first month after surgery. Statistical analysis was performed using STATA v14.

Results :
Age, gender, ethnicity and pre-op BCVA, IOP and number ocular hypotensive drugs did not differ between groups (p>0.05). Mean IOP and number of ocular hypotensive drugs decreased significantly in both groups at 1-month (AGV: 28.6±7.1 to 15.0±17 mmHg, 3.4±0.7 to 1.4±0.8 meds; XAB 34.5±8.7 to 15.6±8.4 mmHg, 2.9±0.7 to 0.7±0.9 meds) (all changes p<0.001). IOP at 1-month was not different between groups (p=0.84). In 4 (36%) AGV patients and 2 (18%) XAB cases a hypertensive phase with need for topical medication was noted, with 6 (55%) AGV patients and 3 (27%) XAB patients under 2 or more drugs at 1-month, respectively. A trend for an increased number of hypotensive drugs in the AGV group at 1-month was observed (1.4±0.8 vs. 0.7±0.9 in XAB) (p=0.08). In the 10 patients under oral acetazolamide, this drug was withdrawn after surgery in all cases. Regarding safety, mean IOP at day 1 was 12.4±6.8 mmHg in the AGV group and 15.4±9.5 mm Hg in the XAB group (p=0.49). Only one case of hypotony (4 mmHg) occurred, in the AGV group. Mean BCVA did not change significantly with the procedure in both groups (p>0.05).

Conclusions :
Our results suggest that XAB was comparable to AGV in terms of early safety and efficacy outcomes, along with an apparently less pronounced hypertensive phase after the first month. Since Baerveldt tube may have advantages in the long-term IOP control comparing to fluid-restrictive devices, XAB may be a promising modified technique with a favorable safety profile.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.